Selective Measurement of Water Content in Multivariable Biofuel Using Microstrip Split Ring Resonators

Abstract—As biofuel usage grows in popularity, biofuel contamination by water becomes a very important issue. Therefore, real-time monitoring of water content in biofuel is critical. This paper presents a split ring resonator-based sensor for measurement of the volumetric percentage of biofuel components. The biofuel of interest, E85, consists of three components: ethanol, gasoline, and water. To account for this, measurement features are introduced in this work by analyzing frequency shifts of the fundamental resonance and higher harmonics of a split ring resonator. Impressive precision in the volumetric measurement of the components of homogeneous mixtures is achieved with the total mean-square error of less than 0.85%.